Get all the Gropus of Current Login User

using Microsoft.SharePoint.Client;



public void GetCurrentUserGroups(string url)
{

    try

    {

        using(ClientContext _context = new ClientContext(url))

        {

            _context.Credentials = System.Net.CredentialCache.DefaultCredentials;

            User currentuser = _context.Web.CurrentUser;

            GroupCollection currentuserGroups = currentuser.Groups;

            _context.Load(currentuserGroups);

            _context.ExecuteQuery();

            foreach(var group in currentuserGroups)

            {

                Console.WriteLine(group.Title);

            }

        }

    } catch (Exception)

    {

        throw;

    }

}